I. Field of the Invention
This invention is related generally to the construction of retaining wall blocks, and more particularly to a unique method of forming a pair of identical blocks each with a raised front lip and a lower front recess, the depth of which lower recess can be selectively defined during the manufacturing process to correspond to the setback angle of a retaining wall which can be constructed from the block.
II. Discussion of the Prior Art
Retaining walls are commonly employed to retain highly positioned soil, such as soil forming a hill, to provide a usable level surface therebelow such as for playgrounds and yards, or to provide artificial contouring of the landscape which is aesthetically pleasant. Retaining wall systems are typically designed to have a "setback" at an angle to counter the pressure of the soil disposed behind the wall. Setback is generally considered to be the distance in which one course of a wall extends beyond the front of the next highest course of the same wall. However, setback is not always required for a wall of moderate height, and further, may not be appropriate when constructed close to lot lines, utilities, trees, or structures already in place. Thus, a method of manufacturing retaining wall blocks which accommodates selectively creating blocks of different dimensions such that the blocks can be used to form retaining walls with setbacks from 0.degree. to 12.degree. would be valuable to accommodate the needs of various applications.
It is known in the prior art to form blocks in pairs, whereupon a composite block is split to form a pair of substantially identical blocks to economize the production of the blocks. Further, splitting a composite block allows the formation of an irregular and aesthetically pleasant textured front surface for each of the blocks defined. Thus, splitting a molded composite block has the dual function of facilitating an economical method of producing multiple blocks from a single mold, and which blocks have an aesthetically pleasant exposed front surface.
U.S. Pat. No. 4,909,010 which is assigned to the assignee of the present invention discloses a novel block having a textured front surface, and which is ideal for constructing retaining wall systems with a setback. The blocks interlock to create a strong barrier wall. The setback is determined by the thickness of the front lip. The blocks are formed in pairs by splitting a single molded block. There is no lower channel defined in the molded block, thus, a wall cannot be built with no setback. There is also no method disclosed of using a single mold to define blocks of different shapes and dimensions.
U.S. Pat. No. 5,017,049 to Sievert teaches a composite masonry block which facilitates creating a retaining wall with setback, and which blocks are formed in pairs by splitting a block along a midsection thereof to define a pair of substantially identical blocks. A pair of longitudinally extending grooves are defined parallel to each other, one defined in the upper major surface and the other in the lower major surface of the block. Upon splitting the block, a pair of substantially identical blocks are formed, each having a textured front surface. A pair of opposing flanges are defined on the composite block such that upon splitting, each formed block will have a downwardly extending rear flange to facilitate establishing a predetermined setback. The method taught includes filling the mold cavities in a manner which provides for casting the blocks on their sides. The method taught by this patent facilitates creating blocks in an economical manner, but fails to teach a method of forming a block with selectively defined dimensions, and from a single mold such that the blocks can ultimately form retaining walls with a chosen setback, or with no setback at all.
U.S. Pat. No. 5,031,376 to Bender et al. teaches retaining wall construction and blocks which are also formed in pairs. During manufacturing, a pair of grooves are defined parallel to another, one disposed in each of the major surfaces to facilitate the splitting procedure. A pair of opposing flanges are defined in the upper major surface at opposite ends thereof, which flanges form a front lip to facilitate a retaining wall with a setback. This block and a method of manufacturing thereof does not facilitate selectively defining dimensions of a retaining wall block using a single mold, which blocks can be used to form a retaining wall with a desired setback, or no setback at all. The face proximate the lip is not textured.
U.S. Pat. No. 4,920,712 to Dean, Jr. teaches a concrete retaining wall block which is formed in pairs by splitting a larger block along the midsection thereof, wherein the front and exposed surface of the block is visible when stacked to form a retaining wall. However, there is no method of manufacturing taught using a single mold wherein the block dimensions can be selectively defined to facilitate creating a retaining wall with a selected setback, or no setback at all.
U.S. Pat. No. 5,214,898 to Beretta teaches a block for building retaining walls having a lip and groove arrangement such that the block can be stacked to form a retaining wall with no setback at all. However, there is no method of manufacturing taught wherein the block dimensions can be selectively defined using a single mold such that the blocks can be used to form a retaining wall with a selected setback, nor is there a method of manufacturing taught wherein the blocks are formed in pairs.